May 20, 2013

Researchers Uncover Our Sun’s Most Distant Solar Twin

Our knowledge of how stars evolve arises out of our survey of billions of stars within and outside of our galaxy. As we piece together the snapshots of these stars of various sizes and masses, at various stages of their evolution, we begin to get a complete picture of how stars are born, live, and die.

Of course, stars most similar to our Sun are perhaps the most relevant as they can tell us about our Sun´s past and its possible future. Now, a team of researchers led by Jose Dias do Nascimento, from the Department of Theoretical and Experimental Physics, Universidade Federal do Rio Grande do Norte, Brazil, has announced the most distant “twin” to our Sun ever detected.

Initially studied with the Subaru Telescope, several candidate stars were studied to find the one that most strongly fit the mass and composition of our Sun. The team then turned their attention to the CoRoT instrument that then allowed them to study and measure the rotation period of the candidate “twin”, CoRoT Sol 1.

The CoRoT satellite (Convection, Rotation and planetary Transits) indicated that the star has a rotation period of 29 +/- 5 days. (For reference the equatorial rotation period of our Sun is just under 25 Earth days; somewhat less, but barely within the error margin of the measurement.) Previous measurements, by various instruments, have had difficulty identifying the rotation periods of all but the youngest stars.

Spectral measurements of the star from the High Dispersion Spectrograph (HDS) on the Subaru Telescope reveal an age of about 6.7 billion years old — some two billion more than our central star. Data from this star can give us a glimpse of what our solar system might be like in a few billion years.

Team leader Dr. Jose Dias do Nascimento noted in a statement: "In two billion years' time, about the solar twin's actual age, the Sun's radiation may increase and make the Earth's surface so hot that liquid water can no longer exist there in its natural state."

The research paper entitled "The Future of the Sun: An Evolved Solar Twin Revealed by CoRoT" has been accepted and will be published in the Astrophysical Journal Letters.